Allow FormatParameterMismatch to be called using Kernel

rrosenblum · rrosenblum · commit f3a0cd73917a · 2015-09-10T23:06:58.000-04:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -12,6 +12,7 @@
 * [#2213](https://github.com/bbatsov/rubocop/issues/2213): Write to cache with binary encoding to avoid transcoding exceptions in some locales. ([@jonas054][])
 * [#2218](https://github.com/bbatsov/rubocop/issues/2218): Fix loading config error when safe yaml is only partially loaded. ([@maxjacobson][])
 * [#2161](https://github.com/bbatsov/rubocop/issues/2161): Allow an explicit receiver (except `Kernel`) in `Style/SignalException`. ([@lumeet][])
+* [#2237](https://github.com/bbatsov/rubocop/pull/2237): Allow `Lint/FormatParameterMismatch` to be called using `Kernel.format` and `Kernel.sprintf`. ([@rrosenblum][])
 
 ## 0.34.0 (05/09/2015)
 
diff --git a/lib/rubocop/cop/lint/format_parameter_mismatch.rb b/lib/rubocop/cop/lint/format_parameter_mismatch.rb
@@ -17,6 +17,7 @@ class FormatParameterMismatch < Cop
         # rubocop:disable Metrics/LineLength
         FIELD_REGEX = /(%(([\s#+-0\*])?(\d*)?(.\d+)?(\.)?[bBdiouxXeEfgGaAcps]|%))/
         NAMED_FIELD_REGEX = /%\{[_a-zA-Z][_a-zA-Z]+\}/
+        KERNEL = 'Kernel'.freeze
 
         def fields_regex
           FIELD_REGEX
@@ -87,8 +88,11 @@ def count_matches(node)
         def format_method?(name, node)
           receiver, method_name, *args = *node
 
-          # commands have no explicit receiver
-          return false unless !receiver && method_name == name
+          if receiver && receiver.const_type?
+            return false unless receiver.loc.name.is?(KERNEL)
+          end
+
+          return false unless method_name == name
 
           args.size > 1 && :str == args.first.type
         end
diff --git a/spec/rubocop/cop/lint/format_parameter_mismatch_spec.rb b/spec/rubocop/cop/lint/format_parameter_mismatch_spec.rb
@@ -5,6 +5,24 @@
 describe RuboCop::Cop::Lint::FormatParameterMismatch do
   subject(:cop) { described_class.new }
 
+  it 'registers an offense when calling Kernel.format ' \
+     'and the fields do not match' do
+    inspect_source(cop, 'Kernel.format("%s %s", 1)')
+    expect(cop.offenses.size).to eq(1)
+
+    msg = ['Number arguments (1) to `format` mismatches expected fields (2).']
+    expect(cop.messages).to eq(msg)
+  end
+
+  it 'registers an offense when calling Kernel.sprintf ' \
+     'and the fields do not match' do
+    inspect_source(cop, 'Kernel.sprintf("%s %s", 1)')
+    expect(cop.offenses.size).to eq(1)
+
+    msg = ['Number arguments (1) to `sprintf` mismatches expected fields (2).']
+    expect(cop.messages).to eq(msg)
+  end
+
   it 'registers an offense when there are less arguments than expected' do
     inspect_source(cop, 'format("%s %s", 1)')
     expect(cop.offenses.size).to eq(1)
